A view is a callable which takes a request and returns a\nresponse. This can be more than just a function, and Django provides\nan example of some classes which can be used as views. These allow you\nto structure your views and reuse code by harnessing inheritance and\nmixins. There are also some generic views for tasks which we'll get to later,\nbut you may want to design your own structure of reusable views which suits\nyour use case. For full details, see the class-based views reference\ndocumentation.
\n\nDjango provides base view classes which will suit a wide range of applications.\nAll views inherit from the View class, which\nhandles linking the view into the URLs, HTTP method dispatching and other\ncommon features. RedirectView provides a\nHTTP redirect, and TemplateView extends the\nbase class to make it also render a template.
The most direct way to use generic views is to create them directly in your\nURLconf. If you're only changing a few attributes on a class-based view, you\ncan pass them into the as_view() method\ncall itself:
from django.urls import path\nfrom django.views.generic import TemplateView\n\nurlpatterns = [\n path('about/', TemplateView.as_view(template_name="about.html")),\n]\nas_view() に渡されたすべての引数は、クラスで設定された属性を上書きします。次の例では TemplateView の template_name を設定しています。同様の上書きのパターンは、RedirectView の url 属性でも使えます。
The second, more powerful way to use generic views is to inherit from an\nexisting view and override attributes (such as the template_name) or\nmethods (such as get_context_data) in your subclass to provide new values\nor methods. Consider, for example, a view that just displays one template,\nabout.html. Django has a generic view to do this -\nTemplateView - so we can subclass it, and\noverride the template name:
# some_app/views.py\nfrom django.views.generic import TemplateView\n\nclass AboutView(TemplateView):\n template_name = "about.html"\nThen we need to add this new view into our URLconf.\nTemplateView is a class, not a function, so\nwe point the URL to the as_view() class\nmethod instead, which provides a function-like entry to class-based views:
# urls.py\nfrom django.urls import path\nfrom some_app.views import AboutView\n\nurlpatterns = [\n path('about/', AboutView.as_view()),\n]\n組み込みのジェネリックビューの使用方法の詳細については、次のトピック generic class-based views を参照してください。
\n誰かが私たちの図書館に HTTP 経由でアクセスして、ビューを API として使用したいという状況を考えてください。API クライアントはたびたびコネクションを張り、最終訪問日時以降に出版された本のデータをダウンロードするとします。しかし、新しい本の情報が存在しない場合には、データベースから本のデータを取得し、レスポンステキストをレンダリングし、クライアントに送信し返すための CPU タイムとバンド幅は無駄になってしまいます。最新の本が出版された時点で API に問い合わせた方が好ましいかもしれません。
\nそのために、URLconf 内で、本のリストビューへの URL を次のようにマッピングします。
\nfrom django.urls import path\nfrom books.views import BookListView\n\nurlpatterns = [\n path('books/', BookListView.as_view()),\n]\nそして、ビューには次のように書きます。
\nfrom django.http import HttpResponse\nfrom django.views.generic import ListView\nfrom books.models import Book\n\nclass BookListView(ListView):\n model = Book\n\n def head(self, *args, **kwargs):\n last_book = self.get_queryset().latest('publication_date')\n response = HttpResponse()\n # RFC 1123 date format\n response['Last-Modified'] = last_book.publication_date.strftime('%a, %d %b %Y %H:%M:%S GMT')\n return response\nIf the view is accessed from a GET request, an object list is returned in\nthe response (using the book_list.html template). But if the client issues\na HEAD request, the response has an empty body and the Last-Modified\nheader indicates when the most recent book was published. Based on this\ninformation, the client may or may not download the full object list.